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fix a bug in ZFS mirror code for handling multiple DVAa

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The bug was introduced in r256956 "Improve ZFS N-way mirror read
performance".
The code in vdev_mirror_dva_select erroneously considers already
tried DVAs for the next attempt.  Thus, it is possible that a failing DVA
would be retried forever.
As a secondary effect, if the attempts fail with checksum error, then
checksum error reports are accumulated until the original request
ultimately fails or succeeds.  But because retrying is going on indefinitely
the cheksum reports accumulation will effectively be a memory leak.

Reviewed by:	gibbs
MFC after:	13 days
Sponsored by:	HybridCluster
This commit is contained in:
avg 2014-01-16 13:24:10 +00:00
parent d1329f5a22
commit e186f564bc
1 changed files with 6 additions and 3 deletions
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9
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_mirror.c
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@ -313,13 +313,16 @@ vdev_mirror_scrub_done(zio_t *zio)
* single-copy data.
*/
static int
vdev_mirror_dva_select(zio_t *zio, int preferred)
vdev_mirror_dva_select(zio_t *zio, int p)
{
dva_t *dva = zio->io_bp->blk_dva;
mirror_map_t *mm = zio->io_vsd;
int preferred;
int c;
for (c = preferred - 1; c >= 0; c--) {
preferred = mm->mm_preferred[p];
for (p-- ; p >= 0; p--) {
c = mm->mm_preferred[p];
if (DVA_GET_VDEV(&dva[c]) == DVA_GET_VDEV(&dva[preferred]))
preferred = c;
}
@ -334,7 +337,7 @@ vdev_mirror_preferred_child_randomize(zio_t *zio)
if (mm->mm_root) {
p = spa_get_random(mm->mm_preferred_cnt);
return (vdev_mirror_dva_select(zio, mm->mm_preferred[p]));
return (vdev_mirror_dva_select(zio, p));
}
/*